Having machine-readable code on the packaging of a product is a good way to transmit information related to the product. For example, bar code has been used for many years to carry information such as product identification and inventory information. Such bar codes can be optically read to retrieve the information encoded in the bar codes.
However, bar codes are one dimensional and are limited in the amount of information that can be stored. As a result, two dimensional symbology has been developed to increase the amount of data stored by such codes. In using two dimensional codes for recording information, precise synchronization is needed to read the data from the symbol pattern sequentially. To provide orientation for the two dimensional symbology, the techniques of encoding often need visually identifiable features such as lines, frames, concentric rings, axes, columns or rows of symbols, or the like, that are optically discriminatable from other symbols and images. Unfortunately, such techniques are less than desirable if the information is to be embedded in a visual image because the visually identifiable features are obtrusive to a viewer who wants to observe the image without distraction.
What is needed is a technique for encoding and decoding embedded messages within a visual image without obtrusive features representing the embedded message or the synchronization or orientation of the data pattern.
U.S. Pat. No. 4,263,504 (Thomas), U.S. Pat. No. 5,189,292 (Batterman et al), U.S. Pat. No. 5,128,525 (Stearns et al.), U.S. Pat. No. 5,221,833 (Hecht), U.S. Pat. No. 5,245,165 (Zhang), U.S. Pat. No. 5,329,107 (Priddy et al.), U.S. Pat. No. 5,439,354 (Priddy), U.S. Pat. No. 5,481,103 (Wang), U.S. Pat. No. 5,507,527 (Tomioka, et al.), U.S. Pat. No. 5,515,447 (Zheng, et al), U.S. Pat. No. 5,521,372 (Hecht, et al.), U.S. Pat. No. 5,541,396 (Rentsch), U.S. Pat. No. 5,572,010 (Petrie), U.S. Pat. No. 5,576,532 (Hecht), and U.S. Pat. No. 5,591,956 (Longacre, et al.) are examples of descriptions of the use of two dimensional symbology in storing encoded information. The disclosure of these cited patents are incorporated by reference herein in their entirety.